U.S. patent number 10,813,680 [Application Number 15/470,127] was granted by the patent office on 2020-10-27 for cryoballoon contact assessment using capacitive or resistive sensors.
This patent grant is currently assigned to Medtronic CryoCath LP. The grantee listed for this patent is Medtronic CryoCath LP. Invention is credited to Nicolas Coulombe.
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United States Patent |
10,813,680 |
Coulombe |
October 27, 2020 |
Cryoballoon contact assessment using capacitive or resistive
sensors
Abstract
Devices, systems, and methods for assessing contact between a
treatment element and an area of target tissue using resistive-type
and/or capacitive-type contact sensing elements. In one embodiment,
a medical system for determining tissue contact includes an
elongate body including a distal portion and a proximal portion and
a treatment element coupled to the elongate body distal portion.
The treatment element may have a first expandable element, a second
expandable element, the first expandable element being within the
second expandable element, and at least one contact sensing element
between the first and second expandable elements. In one example,
the device may include a plurality of contact sensing elements
arranged in a matrix or in a plurality of linear configurations. In
another example, the device may include a layer of conductive
microparticles or a contact-sensing film.
Inventors: |
Coulombe; Nicolas (Anjou,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Medtronic CryoCath LP |
Toronto |
N/A |
CA |
|
|
Assignee: |
Medtronic CryoCath LP (Toronto,
Ontario, unknown)
|
Family
ID: |
63581671 |
Appl.
No.: |
15/470,127 |
Filed: |
March 27, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180271578 A1 |
Sep 27, 2018 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B
18/02 (20130101); A61B 2090/065 (20160201); A61B
2018/0022 (20130101); A61B 2018/0212 (20130101); A61B
2018/00875 (20130101); A61B 2018/00255 (20130101); A61B
2018/00375 (20130101) |
Current International
Class: |
A61B
18/02 (20060101); A61B 18/00 (20060101); A61B
90/00 (20160101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International Search Report and Written Opinion dated May 8, 2018,
for corresponding International Application No: PCT/CA2018/050214;
International Filing Date: Feb. 26, 2018 consisting of 10-pages.
cited by applicant .
Lee et al., A transparent bending-insensitive pressure sensor,
Nature Nanotechnology, vol. 11, May 2016, pp. 472-479, published
online: Jan. 25, 2016 (Jan. 1, 2016), DOI: 10.1038/NNANO.2015.324.
cited by applicant .
Klinker et al., "Balloon catheters with integrated stretchable
electronics for electrical stimulation, ablation and blood low
monitoring", Extreme Mechanics Letters, vol. 3 (2015), pp. 45-54,
Available Online Feb. 24, 2015 (Feb. 24, 2015), DOI:
10.1016/J.EML.2015.02.005. cited by applicant .
Lee et al., "Catheter-Based Systems With Integrated Stretchable
Sensors and Conductors in Cardiac Electrophysiology", Proceedings
of the IEEE, vol. 103, No. 4, Apr. 2015 (Apr. 2015), DOI:
10.1109/JPROC.2015.2401596. cited by applicant .
Kim et al., "Electronic sensor and actuator webs for large-area
complex geometry cardiac mapping and therapy", Proc Natl Acad Sci U
S A. Dec. 4, 2012; 109(49): 19910-19915, Published online Nov. 12,
2012 (Dec. 11, 2012), DOI: 10.1073/pnas.1205923109. cited by
applicant.
|
Primary Examiner: Peffley; Michael F
Assistant Examiner: Good; Samantha M
Attorney, Agent or Firm: Christopher & Weisberg,
P.A.
Claims
What is claimed is:
1. A medical device for determining tissue contact, the device
comprising: an elongate body including a distal portion and a
proximal portion; and a treatment element coupled to the distal
portion of the elongate body, the treatment element having: a first
expandable element; a second expandable element, the first
expandable element being within the second expandable element; a
plurality of spacers spaced apart from one another and configured
to maintain a distance between the first expandable element and the
second expandable element; at least one contact sensing element
between the first and second expandable elements, the at least one
contact sensing element containing a low density material with
conductive microparticles; and wherein the first expandable element
has an inner surface and an outer surface, the at least one contact
sensing element being on an outer surface of the first expandable
element.
2. The medical device of claim 1, wherein the at least one contact
sensing element is in electrical communication with a
multiplexer.
3. The medical device of claim 2, wherein the device further
comprises a shaft having a distal tip, the multiplexer being
located at the distal tip of the shaft.
4. The medical device of claim 1, wherein the treatment element
further includes an interstitial space between the first and second
expandable elements, the at least one contact sensing element being
in the interstitial space.
5. A medical system for determining tissue contact, the system
comprising: a medical device including: an elongate body including
a distal portion and a proximal portion; and a treatment element
coupled to the distal portion of the elongate body, the treatment
element having: a first expandable element; a second expandable
element, the first expandable element being within the second
expandable element; at least one contact sensing element between
the first and second expandable elements, the at least one contact
sensing element containing a low density material with conductive
microparticles; wherein the first expandable element has an inner
surface and an outer surface, the at least one contact sensing
element being on an outer surface of the first expandable element;
a plurality of spacers spaced apart from one another and configured
to maintain a distance between the first expandable element and the
second expandable element; and a control unit in communication with
the medical device.
6. The medical system of claim 5, wherein the control unit
includes: processing circuitry in communication with the at least
one contact sensing element; and a display in communication with
the processing circuitry.
7. The medical system of claim 6, wherein the at least one contact
sensing element is configured to transmit electrical signals to the
processing circuitry, the processing circuitry being configured to
identify at last one area of the treatment element that is in
contact with tissue based on the electrical signals received from
the at least one contact sensing element.
8. The medical system of claim 7, wherein the processing circuitry
is configured to show the identified at least one area of contact
on an image of at least a portion of the treatment element.
9. The medical system of claim 7, wherein the conductive
microparticles have a first conductivity when uncompressed and a
second conductivity when compressed, the second conductivity being
greater than the first conductivity.
10. A method for determining tissue contact, the method comprising:
positioning at least a portion of a treatment element of a medical
device in contact with an area of tissue, the treatment element
including: a first expandable element; a second expandable element,
the first expandable element being within the second expandable
element, the first and second expandable elements defining an
interstitial space therebetween; at least one contact sensing
element in the interstitial space, the at least one contact sensing
element containing a low density material with conductive
microparticles; wherein the first expandable element has an inner
surface and an outer surface, the at least one contact sensing
element being on an outer surface of the first expandable element;
and a plurality of spacers spaced apart from one another and
configured to maintain a distance between the first expandable
element and the second expandable element; and recording at least
one electrical signal with the at least one contact sensing element
and transmitting the at least one electrical signal to a control
unit; identifying with the control unit at least one area of
contact between the treatment element and tissue based on the at
least one electrical signal; and displaying the at least one area
of contact, the display including an image of at least a portion of
the treatment element.
Description
CROSS-REFERENCE TO RELATED APPLICATION
n/a
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
n/a
TECHNICAL FIELD
The present invention relates to a method and system for
determining contact between a treatment element and tissue based on
signals from one or more contact sensing elements located within
the treatment element. The one or more contact sensing elements may
be resistive-type and/or capacitive-type contact sensors.
BACKGROUND
Cardiac arrhythmia, a group of disorders in which the heart's
normal rhythm is disrupted, affects millions of people. Certain
types of cardiac arrhythmias, including ventricular tachycardia and
atrial fibrillation, may be treated by ablation (for example,
radiofrequency (RF) ablation, cryoablation, microwave ablation, and
the like), either endocardially or epicardially.
The effectiveness of an ablation procedure may largely depend on
the quality of contact between the treatment element of the medical
device and the cardiac tissue. Procedures such as pulmonary vein
isolation (PVI) are commonly used to treat cardiac arrhythmias such
as atrial fibrillation. In such a procedure, the treatment element
may be positioned at the pulmonary vein ostium in order to create a
circumferential lesion surrounding the ostium. However, proper
positioning of the treatment element to create a complete
circumferential lesion may be challenging.
Some current methods of assessing or monitoring tissue contact may
include intra cardiac echocardiography, trans-esophageal
echography, magnetic resonance imaging, or other currently used
imaging methods. For example, current methods of assessing
pulmonary vein (PV) occlusion include fluoroscopic imaging of
radiopaque contrast medium injected from the device into the PV. If
the treatment element, such as a cryoballoon, has not completely
occluded the PV ostium, some of the contrast medium may flow from
the PV into the left atrium. In that case, the cryoballoon may be
repositioned and more contrast medium injected into the PV. This
method not only necessitates the use of an auxiliary imaging
system, but it also exposes the patient to potentially large doses
of contrast medium and radiation. Additionally, contrast media
techniques cannot accurately determine an exact area where lack of
contact occurs, cannot be used to determine if complete
circumferential contact is maintained throughout the procedure
(such as an ablation procedure), and does not easily provide
information about the effects of micro-movements of the treatment
element on the quality of contact in real time.
Other contact assessment techniques may include using impedance,
temperature, or pressure measurements. However, these methods may
produce inconclusive results, as such data may be difficult to
accurately measure. Further, sensors for these characteristics may
not be located on an entirety of, or even most of, the treatment
element. Therefore using impedance, temperature, pressure, or other
such characteristics may not provide useful information about a
contact status of the treatment element at enough locations to give
a complete indication of tissue contact. Still other techniques
such as pressure monitoring through the guidewire lumen, CO.sub.2
monitoring, or the like cannot be used to pinpoint the exact
location of inadequate tissue contact in real time.
Additionally, using sensors on balloons of devices designed for
intracardiac use may present problems. For example, it may be
difficult to secure the sensor(s) to the balloon material and avoid
peeling or dislodgement of the sensor(s) during manipulation.
Additionally, exposing the sensor(s) to blood, which is highly
conductive, may affect sensor measurements.
SUMMARY
The present invention advantageously provides devices, systems, and
methods for assessing contact between a treatment element and an
area of target tissue using resistive-type and/or capacitive-type
contact sensing elements. In one embodiment, a medical system for
determining tissue contact includes an elongate body including a
distal portion and a proximal portion and a treatment element
coupled to the elongate body distal portion. The treatment element
may have a first expandable element, a second expandable element,
the first expandable element being within the second expandable
element, and at least one contact sensing element between the first
and second expandable elements.
In one aspect of the embodiment, the at least one contact sensing
element includes a plurality of contact sensing elements. In one
aspect of the embodiment, the plurality of contact sensing elements
is in electrical communication with a multiplexer. In one aspect of
the embodiment, the device further comprises a shaft having a
distal tip, the multiplexer being located at the shaft distal
tip.
In one aspect of the embodiment, the first expandable element has
an inner surface and an outer surface, the at least one contact
sensing element being on an outer surface of the first expandable
element.
In one aspect of the embodiment, the second expandable element has
an inner surface and an outer surface, the at least one contact
sensing element being on an inner surface of the second expandable
element.
In one aspect of the embodiment, the treatment element further
includes an interstitial space between the first and second
expandable elements, the at least one contact sensing element being
in the interstitial space. In one aspect of the embodiment, the
plurality of sensing elements is a matrix of sensing elements.
In one aspect of the embodiment, the plurality of sensing elements
is configured in a linear array. In one aspect of the embodiment,
the treatment element has a distal end and a proximal end, the
plurality of sensing elements being a plurality of splines, each of
the plurality of splines extending at least partially between the
distal end and proximal end of the treatment element.
In one aspect of the embodiment, the at least one contact sensing
element is a material containing a low density of conductive
microparticles.
In one aspect of the embodiment, the at least one contact sensing
element is a capacitive touch film.
In one embodiment, a medical system for determining tissue contact
includes: a medical device including: an elongate body including a
distal portion and a proximal portion; and a treatment element
coupled to the elongate body distal portion, the treatment element
having: a first expandable element; a second expandable element,
the first expandable element being within the second expandable
element; and at least one contact sensing element between the first
and second cryoballoons; and a control unit in communication with
the medical device.
In one aspect of the embodiment, the control unit includes:
processing circuitry in communication with the at least one contact
sensing element; and a display in communication with the processing
circuitry. In one aspect of the embodiment, the at least one
contact sensing element is configured to transmit electrical
signals to the processing circuitry, the processing circuitry being
configured to identify at last one area of the treatment element
that is in contact with tissue based on the electrical signals
received from the at least one contact sensing element. In one
aspect of the embodiment, the processing circuitry is configured to
show the identified at least one area of contact on an image of at
least a portion of the treatment element.
In one aspect of the embodiment, the at least one contact sensing
element is a plurality of contact sensing elements arranged in a
matrix.
In one aspect of the embodiment, the at least one contact sensing
element is a plurality of linear contact sensing elements.
In one aspect of the embodiment, the at least one contact sensing
element is a material having a plurality of microparticles having a
first conductivity when uncompressed and a second conductivity when
compressed, the second conductivity being greater than the first
conductivity.
In one embodiment, a method for determining tissue contact
includes: positioning at least a portion of a treatment element of
a medical device in contact with an area of tissue, the treatment
element including: a first expandable element; a second expandable
element, the first expandable element being within the second
expandable element, the first and second expandable elements
defining an interstitial space therebetween; and at least one
contact sensing element in the interstitial space; recording
electrical signals with the at least one contact sensing element
and transmitting the electrical signals to a control unit;
identifying with the control unit at least one area of contact
between the treatment element and tissue based on the electrical
signals; and displaying the at least one area of contact, the
display including an image of at least a portion of the treatment
element.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present invention, and the
attendant advantages and features thereof, will be more readily
understood by reference to the following detailed description when
considered in conjunction with the accompanying drawings
wherein:
FIG. 1 shows an exemplary medical treatment system;
FIG. 2 shows a first close-up, partial cutaway view of a distal
portion of a treatment device having a plurality of contact
sensors;
FIG. 3 shows a front view of the distal portion of the treatment
device shown in FIG. 2, with an outer balloon removed;
FIG. 4 shows a second close-up, partial cutaway view of a distal
portion of a treatment device having a plurality of contact
sensors;
FIG. 5 shows a front view of the distal portion of the treatment
device shown in FIG. 4, with an outer balloon removed;
FIG. 6 shows a third close-up, partial cutaway view of a distal
portion of a treatment device having a contact sensor;
FIG. 7 shows a fourth close-up, partial cutaway view of a distal
portion of a treatment device having contact sensing
capabilities;
FIG. 8 shows a fifth close-up, partial cutaway view of a distal
portion of a treatment device having a contact sensing element;
FIG. 9 shows a sixth close-up, partial cutaway view of a distal
portion of a treatment device having a contact sensing element;
FIG. 10 shows a seventh close-up, partial cutaway view of a distal
portion of a treatment device having a contact sensing element;
FIG. 11 shows a first simplified medical treatment system with
informational display;
FIG. 12 shows a second simplified medical treatment system with
informational display; and
FIG. 13 shows a third simplified medical treatment system with
informational display.
DETAILED DESCRIPTION
The devices, systems, and methods disclosed herein are for
assessing contact between a treatment element and an area of target
tissue using resistive-type and/or capacitive-type contact sensing
elements. In one embodiment, a medical system for determining
tissue contact includes an elongate body including a distal portion
and a proximal portion and a treatment element coupled to the
elongate body distal portion. The treatment element may have a
first expandable element, a second expandable element, the first
expandable element being within the second expandable element, and
at least one contact sensing element between the first and second
expandable elements. In one example, the device may include a
plurality of contact sensing elements arranged in a matrix or in a
plurality of linear configurations. In another example, the device
may include a layer of conductive microparticles or a
contact-sensing film.
Before describing in detail exemplary embodiments that are in
accordance with the disclosure, it is noted that components have
been represented where appropriate by conventional symbols in
drawings, showing only those specific details that are pertinent to
understanding the embodiments of the disclosure so as not to
obscure the disclosure with details that will be readily apparent
to those of ordinary skill in the art having the benefit of the
description herein.
As used herein, relational terms, such as "first," "second," "top"
and "bottom," and the like, may be used solely to distinguish one
entity or element from another entity or element without
necessarily requiring or implying any physical or logical
relationship or order between such entities or elements. The
terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of the concepts
described herein. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises," "comprising," "includes" and/or
"including" when used herein, specify the presence of stated
features, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof.
Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
disclosure belongs. It will be further understood that terms used
herein should be interpreted as having a meaning that is consistent
with their meaning in the context of this specification and the
relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
In embodiments described herein, the joining term, "in
communication with" and the like, may be used to indicate
electrical or data communication, which may be accomplished by
physical contact, induction, electromagnetic radiation, radio
signaling, infrared signaling or optical signaling, for example.
One having ordinary skill in the art will appreciate that multiple
components may interoperate and modifications and variations are
possible of achieving the electrical and data communication.
Referring now to the drawing figures in which like reference
designations refer to like elements, an embodiment of a medical
system is shown in FIG. 1, generally designated as "10." The device
components have been represented where appropriate by conventional
symbols in the drawings, showing only those specific details that
are pertinent to understanding the embodiments of the present
invention so as not to obscure the disclosure with details that
will be readily apparent to those of ordinary skill in the art
having the benefit of the description herein. Moreover, while
certain embodiments or figures described herein may illustrate
features not expressly indicated on other figures or embodiments,
it is understood that the features and components of the system and
devices disclosed herein are not necessarily exclusive of each
other and may be included in a variety of different combinations or
configurations without departing from the scope and spirit of the
invention.
One embodiment of the system 10 may generally include a treatment
device 12 in communication with a control unit 14. The treatment
device 12 may include one or more diagnostic or treatment elements
18 for energetic or other therapeutic interaction between the
device 12 and a treatment site. The treatment element(s) 18 may
deliver, for example, cryogenic therapy, and may further be
configured to deliver radiofrequency energy, or otherwise for
energetic transfer with a tissue area in proximity to the treatment
region(s), including cardiac tissue. In particular, the one or more
treatment elements 18 may be configured to reduce the temperature
of adjacent tissue in order to perform cryotreatment and/or
cryoablation. For example, the treatment region(s) 18 may include
one or more balloons (as shown in FIG. 1) within which a cryogenic
coolant may be circulated in order to reduce the temperature of the
balloon. Additionally, the treatment region(s) 18 may include other
thermally and/or electrically-conductive components, such as one or
more electrodes in communication with the control unit 14.
The device 12 may include an elongate body 20 passable through a
patient's vasculature and/or positionable proximate to a tissue
region for diagnosis or treatment, such as a catheter, sheath, or
intravascular introducer. The elongate body 20 may define a
proximal portion 24 and a distal portion 26, and may further
include one or more lumens disposed within the elongate body 20
that provide mechanical, electrical, and/or fluid communication
between the proximal portion 24 of the elongate body 20 and the
distal portion 26 of the elongate body 20. Further, the one or more
treatment regions 18 (such as the balloon shown in FIG. 1) may be
coupled to the elongate body distal portion 26.
The one or more treatment elements 18 may include a single
expandable element, as shown in the figures. However, it will be
understood that the device may include more than one treatment
element, including expandable and/or non-expandable treatment
elements, electrodes, or other suitable energy exchange structures
or components. As shown in FIG. 1, the expandable element may
include a first balloon, such as a cryoballoon 30A, that has a
proximal end 32A and a distal end 34A, and a second balloon, such
as a cryoballoon 30B, that has a proximal end 32B and a distal end
34B. Together the first 30A and second 30B cryoballoon may be
considered the expandable element of the treatment element 18 and
may collectively be referred to herein as the cryoballoon 30. Also,
the proximal ends 32A, 32B may be referred to herein as the
proximal neck 32 of the expandable element 30 and the distal ends
34A, 34B may be referred to herein as the distal neck 34 of the
expandable element 30. The expandable element proximal end 32 may
be coupled to the elongate body distal portion 26 and the
expandable element distal end 34 may be coupled to a shaft 40 using
any suitable means. Further, the treatment element may define an
interstitial space between the inner 30A and outer 30B
cryoballoons. The inner 30A and outer 30B cryoballoons may be
composed of the same material and may have the same degree of
flexibility or compliance. Alternatively, the cryoballoons 30A, 30B
may be composed of different materials that have different
compliance characteristics. For example, the inner cryoballoon 30A
may be at least substantially non-compliant, whereas the outer
cryoballoon 30B may be at least substantially compliant.
The shaft 40 may be longitudinal movable within a lumen of the
elongate body 20, such that the shaft may be advanced or retracted
within the elongate body 20, and this movement of the shaft 40 may
affect the shape and configuration of the cryoballoon 30. For
example, the shaft 40 may be fully advanced when the cryoballoon is
deflated and in a delivery (or first) configuration wherein the
cryoballoon has a minimum diameter suitable, for example, for
retraction of the device 12 within a sheath for delivery to and
removal from the target treatment site. Conversely, when the
cryoballoon is inflated and in a treatment (or second)
configuration, the shaft may be advanced or retracted over a
distance that affects the size and configuration of the inflated
cryoballoon 30. Further, the shaft 40 may include a guidewire lumen
through which a sensing device, mapping device, guidewire, or other
system component may be located and extended from the distal end of
the device 12.
The device 12 may further include a plurality of flexible contact
sensing elements 44 disposed between the inner (or first)
cryoballoon 30A and the outer (or second) cryoballoon 30B. For
example, the plurality of contact sensing elements 44 may be a
plurality of electrodes arranged in a matrix, mesh, or grid pattern
(for example, as shown in FIGS. 2 and 3). The contact sensing
elements 44 may be printed, deposited, adhered, embedded into,
integrated with the material of, or otherwise at least partially
present on the outer surface of the inner cryoballoon 30A or on the
inner surface of the outer cryoballoon 30B. Additionally or
alternatively, the contact sensing elements 44 may be unattached
structures located between, and optionally held in place by, the
cryoballoons 30A, 30B. In any configuration, however, the contact
sensing element(s) 44 may be referred to as being between the inner
30A and outer 30B cryoballoons or within the interstitial space. As
a non-limiting example, each contact sensing element 44 may be an
area of one or both of the cryoballoons 30A, 30B in which the
balloon material is doped with, embedded with, or having a
deposited or printed layer of a biocompatible material with a
predetermined conductivity selected based on the specific design of
the sensor. Conductive materials may include conductive carbon
including nanotubes, silver, gold, or transparent conductive oxides
such as indium tin oxide, silicon indium oxide, tin oxide, or
others. Materials such as inorganic conductive particles or
conducting polymers may also be used for a resistive layer.
Alternatively, other recently developed materials such as
conductive polydimethylsiloxane, or microstructured conducting
polymers made from interconnected hollow-sphere structures of
polypyrrole may be used. Further, the areas in which the contact
sensing elements are located may include microtextural features,
such as ridges, bumps, or the like to enhance pressure measurement
sensitivity.
As noted above, the flexible contact sensing elements 44 may be
located between the inner 30A and outer 30B cryoballoons. This
location advantageously encapsulates the contact sensing elements,
effectively preventing them from dislodging them and exposing them
to blood or other liquids. Additionally, a non-compliant inner
cryoballoon 30A may act as the backbone of the sensor system (that
is, the plurality of contact sensing elements) to impart rigidity
and enable transfer of applied force on the compliant outer balloon
to the sensor. This in turn may lead to a more accurate
representation of the measured forces. In another embodiment, a
plurality of conductive microparticles may be embedded within the
polymeric balloon material, as discussed in more detail below, and
arranged in such a way as to have a lower conductivity when
non-compressed and higher conductivity when compressed. To
effectively compress particles together with increasing force onto
the sensor, a rigid backbone may also be required for adequate
force transfer to the more compliant medium into which the
microparticles are embedded. Using the balloon materials as the
inner and outer substrates for the sensor materials may also lead
to a thinner sensor design since further encapsulation of the
sensor would be redundant. Thus, the treatment element profile may
be kept to a minimum.
A front view of the treatment element 18 is shown in FIG. 3, with
the outer balloon 30B removed for clarity. The matrix of contact
sensing elements 44 may extend from a first location proximate the
distal end 34 of the cryoballoon 30 (for example, a location
immediately proximal to the location at which the cryoballoon
distal end 34 is attached to the shaft 40, as shown in FIG. 1) to a
second location that is proximal to the first location. As
non-limiting examples, the matrix of contact sensing elements 44
may extend to a second location that is just distal to the
cryoballoon 30 midpoint 46 when the cryoballoon 30 is inflated, a
second location that is just proximal to the cryoballoon 30
midpoint 46 when the cryoballoon is inflated, or to a second
location that is immediately distal to the location at which the
cryoballoon proximal end 32 is attached to the elongate body distal
portion 26 (which configuration may be referred to herein as the
matrix extending along an entire length of the cryoballoon 30). The
device 12 may include any number or configuration of contact
sensing elements 44, including those numbers and configurations not
shown in the figures.
Each contact sensing element 44 may be in electrical communication
with a tracing or wire 48 that is in electrical communication with
the control unit 14. Alternatively, more than one sensing element
44 may be in communication with a single tracing or wire.
Alternatively, all of the plurality of sensing elements 44 may be
in electrical communication with a multiplexer 50, which may
consolidate the signals from the plurality of sensing elements 44
and transmit the combined signal to the control unit 14, which the
signal may be separated into component signals by a demultiplexer
in the control unit 14. As a non-limiting example, the shaft 40 may
include a distal tip 52 that is either at least substantially flush
with or extends distal from the cryoballoon distal end 34. The
multiplexer 50 may be located on or within the shaft distal tip 52.
Each contact sensing element 44 may be composed of conductive
metallic materials, conductive polymeric materials, or combinations
thereof. For example, the materials discussed above may be
used.
In one embodiment, the treatment element 18 may function as a
resistive-type touch sensor. An entirety of one of the cryoballoons
30A, 30B may include a conductive material (for example, mixed with
or including a grid of tiny conductive fibers), thereby rendering
the cryoballoon material a conductive layer. The contact sensing
elements 44 may be included on an opposing surface of the other
cryoballoon 30A, 30B. As a non-limiting example, the inner
cryoballoon 30A may include a conductive material and an inner
surface of the outer cryoballoon 30B may include a plurality of
contact sensing elements 44. However, it will be understood that
the outer cryoballoon 30B may include a conductive material and an
outer surface of the inner cryoballoon 30A may include the contact
sensing elements 44 (as shown in FIG. 2). The treatment element 18
may further include a plurality of spacers 54 on the outer surface
of the inner cryoballoon 30A, on the inner surface of the outer
cryoballoon 30B, and/or otherwise located within the interstitial
space between the cryoballoons 30A, 30B (for example, as shown in
FIG. 2. FIG. 3 does not show the spacers, but it will be understood
that they may be included). The spacers 54 may maintain a
separation (the interstitial space) between the inner 30A and outer
30B cryoballoons. When the treatment element 18 is pressed against
tissue, the force may urge the cryoballoons into contact with each
other in areas between the spacers 54. When the conductive contact
sensing element(s) 44 of one cryoballoon come into contact with the
conductive opposing cryoballoon, a current may flow between the
cryoballoons 30A, 30B, and the location of the contact may be
determined by the control unit 14.
In another embodiment, the treatment element 18 may function as a
capacitive-type touch sensor. For example, each of the inner 30A
and outer 30B cryoballoons may be composed of an insulating
material, but include a conductive material, such as a grid of tiny
conducive fibers, so that the cryoballoons 30A, 30B may carry a
small charge. The contact sensing elements 44 may be included on
the inner surface of the outer cryoballoon 30B and/or on the outer
surface of the inner cryoballoon 30A. When the outer cryoballoon
30B comes into contact with tissue, the charge of the outer
cryoballoon 30B in that area may change. The matrix of contact
sensing elements 44 may function as sensors that measure this
change and communicate the location of the change to the control
unit 14.
Referring to FIGS. 4 and 5, an alternative embodiment of a
treatment element 18 is shown. The features of the treatment
element 18 shown in FIGS. 4 and 5 may be the same as or
substantially the same as those of the treatment element shown in
FIGS. 2 and 3. Further, it will be understood that the treatment
element 18 may include spacers 54 if used as a resistive-type touch
sensor. However, the contact sensing elements 44 may be or include
a plurality of splines 56 located between the inner cryoballoon 30A
and the outer cryoballoon 30B (for example, the splines may be
located within the cryoballoon interstitial space). A front view of
the treatment element 18 is shown in FIG. 5, with the outer balloon
30B removed for clarity. Each spline 56 may extend from the
cryoballoon distal end 34 to the cryoballoon proximal end 32, and
may continue to extend in a distal-to-proximal direction within the
elongate body 20, toward the control unit 14. Alternatively, a
proximal end of each spline 56 may be coupled to, and end at, the
elongate body distal portion 26. Further, the spline distal ends
may be coupled to the shaft 40 or shaft distal tip 52. The splines
56 may be symmetrically disposed around the longitudinal axis 58
(or the longitudinal axis of the elongate body, if the device does
not include a shaft 40), like the segments of an orange, in a
basket configuration. Each spline 56 may be in electrical
communication with a tracing or wire, and optionally to a
multiplexer 50. The device 12 may include any number or
configuration of splines 56, including those numbers and
configurations not shown in the figures. The splines may be a
linear array of sensors, wires of conductive material, and/or a
continuous areas of conductive material that is printed, deposited,
adhered, embedded into, integrated with the material of, or
otherwise at least partially present on the outer surface of the
inner cryoballoon 30A, or on the inner surface of the outer
cryoballoon 30B, in a linear arrangement. For simplicity, any of
these configurations may be referred to herein as a spline. The
splines may be composed of one or more materials such as copper,
gold, silver, or any other suitable biocompatible and flexible
conductive metal, polymer, or combination thereof.
Referring to FIG. 6, an alternative embodiment of the treatment
element is shown, in which a layer of flexible capacitive touch
film 60 is located between the inner 30A and outer 30B cryoballoons
(for example, the film may be located within the cryoballoon
interstitial space). Rather than including a plurality of
individual contact sensing elements 44, the flexible film 60 shown
in FIG. 6 may be referred to as a single contact sensing element
44. However, the flexible film 60 may be capable of registering a
plurality of simultaneous touch points at any location on the film.
The film 60 may be in electrical communication with the control
unit 14. The film may detect contact between the cryoballoon 30 and
tissue through capacitive changes wherein an electrical charge is
transferred from the tissue to complete a circuit, causing a
voltage drop on that point on the film 60. The outer cryoballoon
30B may be embedded or impregnated with conductive fibers that
allow charge transfer from the tissue to the film 60.
Alternatively, the expandable element may include only one
cryoballoon 30, and the film 60 may be located on an outer surface
of the cryoballoon 30 such that the film 60 directly contacts
tissue when the device is in use. The film may have any suitable
size or configuration. For example, the film 60 may cover less than
an entirety of the outer surface of the inner balloon 30A.
Referring to FIG. 7, an alternative embodiment of the treatment
element is shown, in which the material of the inner cryoballoon
30A and/or the outer cryoballoon 30B may be doped with or may
contain a low density of conductive microparticles 62 that provide
contact sensing capabilities to the treatment element 18.
Alternatively, a material containing the conductive microparticles
62 may be included within the interstitial space between the
cryoballoons 30A, 30B. These microparticles 62 collectively may be
referred to as a contact sensing element 44. This material may
function as a piezoresistive sensor, transducing mechanical strain
into an impedance change. For example, when the cryoballoon(s) 30
are not compressed (that is, not in contact with tissue and
exerting a force against the tissue or receiving a compressive
force from the tissue or other structure), the microparticles, and
therefore the cryoballoon(s) 30, are weakly conductive or have a
relatively high resistance. When the cryoballoon(s) are compressed,
the microparticles 62 may come into contact with each other,
thereby increasing their conductivity and, in turn, conducting a
signal through the cryoballoon(s) 30. As a non-limiting example,
the microparticles 62 may be composed of electrically conductive
carbon, including carbon nanotubes, polypyrrole, polypyrrole-coated
polyurethane, or other suitable materials.
Referring to FIGS. 8-10, additional embodiments of a treatment
element are shown. The features of the treatment element 18 shown
in FIGS. 8-10 may be the same as or substantially the same as those
of the treatment element shown in FIGS. 2 and 3. Further, it will
be understood that the treatment element 18 may include spacers 54
if used as a resistive-type touch sensor. However, the device may
include at least one filamentous contact sensing element 63 located
between the inner cryoballoon 30A and the outer cryoballoon 30B
(for example, the filamentous contact sensing element may be
located within the cryoballoon interstitial space). If the
treatment element 18 includes only one filamentous contact sensing
element 63, the contact sensing element 63 may be wound around the
inner cryoballoon 30A from a proximal location on the cryoballoon
30A to a distal location on the cryoballoon 30A. If the treatment
element 18 includes more than one filamentous contact sensing
element 63, each sensing element may be wound around the inner
cryoballoon 30A from a proximal location on the cryoballoon 30A to
a distal location on the cryoballoon 30A or, alternatively, each
filamentous contact sensing element 63 may at least partially
encircle a circumference of the inner cryoballoon 30A (that is, be
arranged as bands that extend around the shaft longitudinal axis
58).
Further, each filamentous contact sensing element 63 may have a
wavy or undulating pattern (for example, as shown in FIGS. 8 and
9), zigzag pattern (for example, as shown in FIG. 10), or other
configuration that increases the surface area over with the
filamentous contact sensing element(s) 63 is/are disposed while
enabling the balloon to be stretched or deformed without damaging
filaments due to material strain, as well as facilitating
foldability of the balloon when deflated. Like the splines 56
described above, the filamentous contact sensing elements 63 may be
a linear array of sensors, wires of conductive material, and/or a
continuous areas of conductive material that is printed, deposited,
adhered, embedded into, integrated with the material of, or
otherwise at least partially present on the outer surface of the
inner cryoballoon 30A, or on the inner surface of the outer
cryoballoon 30B, or otherwise within the interstitial space. The
filamentous contact sensing elements 63 may be composed of one or
more materials such as copper, gold, silver, or any other suitable
biocompatible and flexible conductive metal, polymer, or
combination thereof.
Referring again to FIG. 1, the device may include one or more
nozzles, orifices, or other fluid delivery elements 64 for
delivering fluid to the interior chamber 66 of the cryoballoon 30.
During operation, coolant may flow from a coolant supply 70 through
a coolant delivery conduit within the cryoablation device elongate
body 20 to the distal portion 26, where the coolant may then enter
the interior chamber 66 of the cryoballoon 30, such as through the
one or more fluid delivery elements 32, where the coolant may
expand to cool the cryoballoon 30. Expanded coolant may then pass
from the interior chamber 66 of the cryoballoon 30 to a coolant
recovery reservoir 72 and/or scavenging system through a coolant
recovery conduit.
The device 12 may further include a handle 76 coupled to the
elongate body proximal portion 24, and the handle 76 may include
one or more steering or deflection components for manipulating the
elongate body 20, the one or more treatment elements 18, and/or
additional components of the device 12. The handle 76 may also
include connectors that are matable directly or indirectly to the
control unit 14 to establish communication between the one or more
components of the device 12 with one or more components of the
control unit 14, as described herein. For example, in an exemplary
system, the coolant supply 70, coolant recovery reservoir 72,
and/or one or more alternative energy sources to supply the
selected modality of treatment to the treatment element(s) 18 (such
as, for example, a radiofrequency generator, ultrasound generator,
light sources, or the like) as well as various control mechanisms
for the system 10 may be housed in the control unit 14. The control
unit 14 may also include one or more computers 78 having one or
more displays 80 and processing circuitry and/or software modules
82. The processing circuitry 82 may be programmed or programmable
to execute the automated operation and performance of the features,
sequences, or procedures described herein. As a non-limiting
example, the processing circuitry 82 may include a memory and a
processor, the memory in communication with the processor and
having instructions that, when executed by the processor, configure
the processor to perform one or more system functions. For example,
the processing circuitry 82 may be configured to receive electrical
signals from the contact sensing element(s) 44 (including the
splines 56 and/or the filamentous contact sensing element(s) 63)
and identify contact locations on the cryoballoon 30 from those
signals. It will be understood that one or more system components
may be physically located outside of the control unit 14; however,
any system components that are not part of the device 12 may be
referred to herein as being located within the control unit 14 for
simplicity.
The device 12 and/or control unit 14 may also include one or more
sensors to monitor the operating parameters throughout the system
10, including for example, pressure, temperature, flow rates,
volume, or the like in the control unit 14, and/or the device 12.
For example, the device 12 may further include one or more
temperature and/or pressure sensors (not shown) proximate the
treatment element(s) 18 for monitoring, recording or otherwise
conveying measurements of conditions within the device 12 or the
ambient environment at the distal portion of the cryoablation
device 12. The sensor(s) may be in communication with the control
unit 14 for initiating or triggering one or more alerts or
therapeutic delivery modifications during operation of the device
12.
Referring now to FIGS. 11-13, simplified medical treatment systems
with informational displays are shown to illustrate the contact
sensing functionality. In all three figures, the system receives
electrical signals from the contact sensing element(s) 44 in the
device 12 and converts those signals to contact location
information, then communicates the contact location information to
the user on one or more displays 80. For example, the electrical
signals may be data regarding areas of contact between the
treatment element 18 and tissue. If the device 12 is used to treat
a pulmonary vein ostium, for example, the display may show at least
a portion of the treatment element 18 for visualization of whether
contact between the cryoballoon 30 and the ostium is entirely
circumferential. Thus, any gaps or areas of missing contact may
quickly and easily be identified and the cryoballoon 30 can be
adjusted prior to ablating or treatment the tissue. In the
non-limiting example shown in FIG. 11, the location information may
be displayed on an image of (for example, a stylized depiction of)
the distal end of the treatment element as a generally irregularly
shaped contact area, the displayed contact area 86 being determined
by the contact sensing element(s) 44 registering contact with the
tissue. In FIG. 11, a gap 88 or area of missing contact is shown in
the bottom (or at the 6 o'clock position, as displayed) between the
cryoballoon 30 and tissue. Based on this information, the user may
reposition the cryoballoon 30 such that cryoballoon 30 is urged
against the tissue at the gap position as well as the other
positions.
The non-limiting example shown in FIG. 13 includes a contact
location information display that is similar to that shown in FIG.
11, as the film 60 may detect a plurality of contact points similar
to the electrode matrix of the device 12 shown in FIGS. 1-3. This
information may be used similarly to that shown in FIG. 11.
In the non-limiting example shown in FIG. 12, the location
information may be displayed as speedometer-type display, with the
plurality of splines 56 being displayed as radially extending
lines. If contact is detected by two adjacent splines 56, the
display area corresponding to the cryoballoon 30 between those
splines 56 is shown as part of the contact area 86. Thus, the
contact area 86 is determined by the contact splines 56 registering
contact with the tissue. In FIG. 12, a gap 88 or area of missing
contact is shown in the bottom (or at the 6 o'clock position, as
displayed) between the cryoballoon 30 and tissue. Based on this
information, the user may reposition the cryoballoon 30 such that
cryoballoon 30 is urged against the tissue at the gap position as
well as the other positions. The system 10 may provide one or more
alerts or other indications (for example, audible or visible
alerts) to the user to indicate that the treatment element is in
complete circumferential contact with the target tissue.
Optionally, the control unit 14 may be configured to automatically
initiate the delivery of cryogenic coolant to the treatment
element, and thus begin the ablation procedure, when complete
circumferential contact is achieved.
Although not shown, it will be understood that similar displays of
information and data may be presented to the user if the treatment
element 18 includes the filamentous contact sensing element(s) of
FIGS. 8-10.
It will be appreciated by persons skilled in the art that the
present invention is not limited to what has been particularly
shown and described herein above. In addition, unless mention was
made above to the contrary, it should be noted that all of the
accompanying drawings are not to scale. A variety of modifications
and variations are possible in light of the above teachings without
departing from the scope and spirit of the invention, which is
limited only by the following claims.
* * * * *